Functional Properties and Bioactivities of Pine Nut (Pinus gerardiana) Protein Isolates and Its Enzymatic Hydrolysates

The functional properties and bioactivities of the pine nut protein isolates (PPI) and its enzymatic hydrolysates (PPH) prepared with Alcalase at 5 %, 10 %, 15 % and 25 % degree of hydrolysis (DH) were studied. The solubility of PPH significantly increased (p < 0.05) with the increase of the DH, while the foaming capacity of PPH was only improved at a low DH. However, enzymatic hydrolysis reduced the emulsifying capacity of PPH. The DPPH radical scavenging and inhibition of linoleic acid oxidation activities of PPH were significantly improved by a low DH (5 %) compared with those of PPH with a higher DH and the original PPI (p < 0.05). The reducing power of PPH at all DH decreased in comparison to that of the original PPI. Potent angiotensin-converting enzyme (ACE) inhibitory peptides could be generated by hydrolysis with Alcalase, and the ACE inhibitory activity of PPH increased (p < 0.05) with the DH. These results revealed that a low degree of enzymatic hydrolysis was appropriate to obtain PPH with improved functional properties and good antioxidant activities, while a high degree of hydrolysis was essential to obtain highly potent ACE inhibitory peptides from PPI. These results suggest that the control of the DH may be an effective strategy to modify specific functional and bioactive properties of PPH, and PPH has potential as a functional food ingredient for related functional and health benefits.